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Message-ID: <CAJ5Y-ebsTCby3sEPN4kYp6TxLEJ1zYk+k2JxSf04Gtv2s-u5RQ@mail.gmail.com> Date: Thu, 14 Aug 2014 16:11:51 -0400 From: Ashwin Chaugule <ashwin.chaugule@...aro.org> To: lkml <linux-kernel@...r.kernel.org> Cc: Catalin Marinas <catalin.marinas@....com>, Mike Turquette <mike.turquette@...aro.org>, Morten Rasmussen <morten.rasmussen@....com>, Arjan van de Ven <arjan@...ux.intel.com>, mingo@...nel.org, peterz@...radead.org, len.brown@...el.com, "linaro-acpi@...ts.linaro.org" <linaro-acpi@...ts.linaro.org>, Arnd Bergmann <arnd@...db.de>, linux-acpi@...r.kernel.org, cpufreq@...r.kernel.org, Patch Tracking <patches@...aro.org>, Ashwin Chaugule <ashwin.chaugule@...aro.org>, rjw@...ysocki.net Subject: Re: [RFC 1/3] ACPI: Add support for Platform Communication Channel + Rafael [corrected email addr] On 14 August 2014 15:57, Ashwin Chaugule <ashwin.chaugule@...aro.org> wrote: > The ACPI 5.0+ spec defines a generic mode of communication > between the OS and a platform such as the BMC or external power > controller. This medium (PCC) is typically used by CPPC > (ACPI CPU Performance management), RAS (ACPI reliability protocol) > and MPST (ACPI Memory power states). > > This patch adds initial support for PCC to be usable by the > aforementioned PCC clients. > > Signed-off-by: Ashwin Chaugule <ashwin.chaugule@...aro.org> > --- > drivers/acpi/Kconfig | 10 +++ > drivers/acpi/Makefile | 1 + > drivers/acpi/pcc.c | 192 ++++++++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 203 insertions(+) > create mode 100644 drivers/acpi/pcc.c > > diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig > index a34a228..16d7c9a 100644 > --- a/drivers/acpi/Kconfig > +++ b/drivers/acpi/Kconfig > @@ -364,6 +364,16 @@ config ACPI_REDUCED_HARDWARE_ONLY > > If you are unsure what to do, do not enable this option. > > +config ACPI_PCC > + bool "ACPI Platform Communication Channel" > + def_bool n > + depends on ACPI > + help > + Enable this option if your platform supports PCC as defined in the > + ACPI spec 5.0a+. PCC is a generic mechanism for the OS to communicate > + with a platform such as a BMC. PCC is typically used by CPPC, RAS > + and MPST. > + > source "drivers/acpi/apei/Kconfig" > > config ACPI_EXTLOG > diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile > index ea55e01..35015fa 100644 > --- a/drivers/acpi/Makefile > +++ b/drivers/acpi/Makefile > @@ -74,6 +74,7 @@ obj-$(CONFIG_ACPI_HED) += hed.o > obj-$(CONFIG_ACPI_EC_DEBUGFS) += ec_sys.o > obj-$(CONFIG_ACPI_CUSTOM_METHOD)+= custom_method.o > obj-$(CONFIG_ACPI_BGRT) += bgrt.o > +obj-$(CONFIG_ACPI_PCC) += pcc.o > > # processor has its own "processor." module_param namespace > processor-y := processor_driver.o processor_throttling.o > diff --git a/drivers/acpi/pcc.c b/drivers/acpi/pcc.c > new file mode 100644 > index 0000000..105e11a > --- /dev/null > +++ b/drivers/acpi/pcc.c > @@ -0,0 +1,192 @@ > +/* > + * Copyright (C) 2014 Linaro Ltd. > + * Author: Ashwin Chaugule <ashwin.chaugule@...aro.org> > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License as published by > + * the Free Software Foundation; either version 2 of the License, or > + * (at your option) any later version. > + * > + * This program is distributed in the hope that it will be useful, > + * but WITHOUT ANY WARRANTY; without even the implied warranty of > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. > + * > + */ > + > +#include <linux/acpi.h> > +#include <linux/io.h> > +#include <linux/uaccess.h> > +#include <linux/init.h> > +#include <linux/cpufreq.h> > +#include <linux/delay.h> > +#include <linux/ioctl.h> > +#include <linux/vmalloc.h> > +#include <linux/module.h> > + > +#include <acpi/actbl.h> > + > +#define MAX_PCC_SUBSPACES 256 > +#define PCCS_SS_SIG_MAGIC 0x50434300 > +#define PCC_CMD_COMPLETE 0x1 > +#define PCC_VERSION "0.1" > + > +struct pcc_ss_desc { > + struct acpi_pcct_subspace *pcc_ss_ptr; > + raw_spinlock_t lock; > +}; > + > +/* Array of pointers to Type 0 Generic Communication Subspace Structures */ > +struct pcc_ss_desc pcc_ss_arr[MAX_PCC_SUBSPACES]; > + > +/* Total number of subspaces detected in PCCT. */ > +static int total_ss; > + > +/* > + * PCC clients call this function to get a base address of their > + * Communication channel > + */ > +int get_pcc_comm_channel(u32 ss_idx, u64 __iomem *addr, int *len) > +{ > + struct acpi_pcct_subspace *pcct_subspace = pcc_ss_arr[ss_idx].pcc_ss_ptr; > + > + if (pcct_subspace) { > + *addr = pcct_subspace->base_address; > + *len = pcct_subspace->length; > + } else > + return -EINVAL; > + > + pr_debug("base addr: %llx\n", pcct_subspace->base_address); > + > + return 0; > +} > + > +/* Send PCC cmd on behalf of this (subspace id) PCC client */ > +u16 send_pcc_cmd(u8 cmd, u8 sci, u32 ss_idx, u64 __iomem *base_addr) > +{ > + struct acpi_pcct_subspace *pcct_subspace = pcc_ss_arr[ss_idx].pcc_ss_ptr; > + struct acpi_pcct_shared_memory *generic_comm_base = > + (struct acpi_pcct_shared_memory *)base_addr; > + struct acpi_generic_address doorbell; > + u64 doorbell_preserve; > + u64 doorbell_val; > + u64 doorbell_write; > + > + /* > + * Min time in usec that OSPM is expected to wait > + * before sending the next PCC cmd. > + */ > + u16 cmd_delay = pcct_subspace->min_turnaround_time; > + > + pr_debug("cmd: %d, ss_idx: %d, addr: %llx\n", cmd, ss_idx, (u64) base_addr); > + if (!generic_comm_base) { > + pr_err("No Generic Communication Channel provided.\n"); > + return -EINVAL; > + } > + > + raw_spin_lock(&pcc_ss_arr[ss_idx].lock); > + > + /* Get doorbell details for this subspace. */ > + doorbell = pcct_subspace->doorbell_register; > + doorbell_preserve = pcct_subspace->preserve_mask; > + doorbell_write = pcct_subspace->write_mask; > + > + /* Write to the shared comm region. */ > + iowrite16(cmd, &generic_comm_base->command); > + > + /* Write Subspace MAGIC value so platform can identify destination. */ > + iowrite32((PCCS_SS_SIG_MAGIC | ss_idx), &generic_comm_base->signature); > + > + /* Flip CMD COMPLETE bit */ > + iowrite16(0, &generic_comm_base->status); > + > + /* Sync notification from OSPM to Platform. */ > + acpi_read(&doorbell_val, &doorbell); > + acpi_write((doorbell_val & doorbell_preserve) | doorbell_write, > + &doorbell); > + > + /* Wait for Platform to consume. */ > + while (!(ioread16(&generic_comm_base->status) & PCC_CMD_COMPLETE)) > + udelay(cmd_delay); > + > + raw_spin_unlock(&pcc_ss_arr[ss_idx].lock); > + > + return generic_comm_base->status; > +} > + > +static int parse_pcc_subspace(struct acpi_subtable_header *header, > + const unsigned long end) > +{ > + struct acpi_pcct_subspace *pcct_ss; > + > + if (total_ss <= MAX_PCC_SUBSPACES) { > + pcct_ss = (struct acpi_pcct_subspace*) header; > + > + if (pcct_ss->header.type != ACPI_PCCT_TYPE_GENERIC_SUBSPACE) { > + pr_err("Incorrect PCC Subspace type detected\n"); > + return -EINVAL; > + } > + > + pcc_ss_arr[total_ss].pcc_ss_ptr = pcct_ss; > + pr_debug("(%s)PCCT base addr: %llx", __func__, pcct_ss->base_address); > + raw_spin_lock_init(&pcc_ss_arr[total_ss].lock); > + > + total_ss++; > + } else { > + pr_err("No more space for PCC subspaces.\n"); > + return -ENOSPC; > + } > + > + return 0; > +} > + > +static int __init pcc_probe(void) > +{ > + acpi_status status = AE_OK; > + acpi_size pcct_tbl_header_size; > + struct acpi_table_pcct *pcct_tbl; > + > + /* Search for PCCT */ > + status = acpi_get_table_with_size(ACPI_SIG_PCCT, 0, > + (struct acpi_table_header **)&pcct_tbl, > + &pcct_tbl_header_size); > + > + if (ACPI_SUCCESS(status) && !pcct_tbl) { > + pr_warn("PCCT header not found.\n"); > + status = AE_NOT_FOUND; > + goto out_err; > + } > + > + status = acpi_table_parse_entries(ACPI_SIG_PCCT, > + sizeof(struct acpi_table_pcct), ACPI_PCCT_TYPE_GENERIC_SUBSPACE, > + parse_pcc_subspace, MAX_PCC_SUBSPACES); > + > + if (ACPI_SUCCESS(status)) > + pr_err("Error parsing PCC subspaces from PCCT\n"); > + > + pr_info("Detected %d PCC Subspaces\n", total_ss); > + > +out_err: > + return (ACPI_SUCCESS(status) ? 1 : 0); > +} > + > +static int __init pcc_init(void) > +{ > + int ret; > + > + if (acpi_disabled) > + return -ENODEV; > + > + /* Check if PCC support is available. */ > + ret = pcc_probe(); > + > + if (ret) { > + pr_debug("PCC probe failed.\n"); > + return -EINVAL; > + } > + > + return ret; > +} > +device_initcall(pcc_init); > + > + > -- > 1.9.1 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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